cp: improve the support of --attributes-only (#6051)

* cp: improve the support of --attributes-only

* remove useless comments

Co-authored-by: Daniel Hofstetter <daniel.hofstetter@42dh.com>

---------

Co-authored-by: Daniel Hofstetter <daniel.hofstetter@42dh.com>

src/uu/cp/src/cp.rs

@@ -780,7 +780,11 @@ impl CopyMode {
         {
             Self::Update
         } else if matches.get_flag(options::ATTRIBUTES_ONLY) {
+            if matches.get_flag(options::REMOVE_DESTINATION) {
+                Self::Copy
+            } else {
                 Self::AttrOnly
+            }
         } else {
             Self::Copy
         }
@@ -1709,7 +1713,13 @@ fn copy_file(
         fs::remove_file(dest)?;
     }
 
-    if file_or_link_exists(dest) {
+    if file_or_link_exists(dest)
+        && (!options.attributes_only
+            || matches!(
+                options.overwrite,
+                OverwriteMode::Clobber(ClobberMode::RemoveDestination)
+            ))
+    {
         if are_hardlinks_to_same_file(source, dest)
             && !options.force()
             && options.backup == BackupMode::NoBackup
@@ -1721,6 +1731,20 @@ fn copy_file(
         handle_existing_dest(source, dest, options, source_in_command_line)?;
     }
 
+    if options.attributes_only
+        && source.is_symlink()
+        && !matches!(
+            options.overwrite,
+            OverwriteMode::Clobber(ClobberMode::RemoveDestination)
+        )
+    {
+        return Err(format!(
+            "cannot change attribute {}: Source file is a non regular file",
+            dest.quote()
+        )
+        .into());
+    }
+
     if options.preserve_hard_links() {
         // if we encounter a matching device/inode pair in the source tree
         // we can arrange to create a hard link between the corresponding names

tests/by-util/test_cp.rs

@@ -3800,3 +3800,58 @@ fn test_acl_preserve() {
 
     assert!(compare_xattrs(&file, &file_target));
 }
+
+#[test]
+fn test_cp_force_remove_destination_attributes_only_with_symlink() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+
+    at.write("file1", "1");
+    at.write("file2", "2");
+    at.symlink_file("file1", "sym1");
+
+    scene
+        .ucmd()
+        .args(&[
+            "-a",
+            "--remove-destination",
+            "--attributes-only",
+            "sym1",
+            "file2",
+        ])
+        .succeeds();
+
+    assert!(
+        at.symlink_exists("file2"),
+        "file2 is not a symbolic link as expected"
+    );
+
+    assert_eq!(
+        at.read("file1"),
+        at.read("file2"),
+        "Contents of file1 and file2 do not match"
+    );
+}
+
+#[test]
+fn test_cp_no_dereference_attributes_only_with_symlink() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+    at.write("file1", "1");
+    at.write("file2", "2");
+    at.write("file2.exp", "2");
+    at.symlink_file("file1", "sym1");
+
+    let result = scene
+        .ucmd()
+        .args(&["--no-dereference", "--attributes-only", "sym1", "file2"])
+        .fails();
+
+    assert_eq!(result.code(), 1, "cp command did not fail");
+
+    assert_eq!(
+        at.read("file2"),
+        at.read("file2.exp"),
+        "file2 content does not match expected"
+    );
+}